The invention discloses a vermicular graphite cast iron piston ring for an internal combustion engine. The vermicular graphite cast iron piston ring comprises a piston ring body, wherein anti-adherent films cover the upper surface, the lower surface, and one surface, facing a position ring groove, of the piston ring body; an abrasion-resistant layer is arranged on the other surface, in contact with a cylinder, of the piston ring body; the abrasion-resistant layer extends along the other surface, in contact with the cylinder, of the piston ring body, to form a first tongue part and a second tongue part; a bulged circular barrel shape is formed on the outer circumferential surface of the first tongue part, and an opening part is formed in the other surface, in contact with the cylinder, of the piston ring body; a bulged circular barrel shape is formed on the outer circumferential surface of the second tongue part, and an opening part is formed in the other surface, in contact with the cylinder, of the piston ring body. The piston ring can remain the adhering preventing effect for a long term under high temperature, so that the problem of non-uniform abrasion of the contact surface of the inner circumferential surface of the cylinder can be solved, and as a result, the comprehensive performance of the piston ring body can be improved, and the piston ring is durable.